MAX8792ETD+T Maxim Integrated Products, MAX8792ETD+T Datasheet - Page 17

• Manufacturer Part Number: MAX8792ETD+T
• Description: IC PWM CONTROLLER 14TDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8792ETD+T

• Applications: PWM Controller
• Voltage - Input: 2 ~ 26 V
• Current - Supply: 700µA
• Operating Temperature: -40°C ~ 80°C
• Mounting Type: Surface Mount
• Package / Case: 14-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Figure 4. High Output-Voltage Application Using a Feedback Divider
Although REFIN is limited to a 0 to 2V range, the out-
put-voltage range is unlimited since the MAX8792 uti-
lizes a high-impedance feedback input (FB). By adding
a resistive voltage-divider from the output to FB to ana-
log ground (Figure 4), the MAX8792 supports output
voltages above 2V. However, the controller also uses
FB to determine the on-time, so the voltage-divider
influences the actual switching frequency, as detailed
in the On-Time One-Shot section.
An integrator amplifier forces the DC average of the FB
voltage to equal the target voltage. This internal amplifi-
er integrates the feedback voltage and provides a fine
adjustment to the regulation voltage (Figure 2), allowing
accurate DC output-voltage regulation regardless of the
compensated feedback ripple voltage and internal
slope-compensation variation. The integrator amplifier
has the ability to shift the output voltage by ±55mV (typ).
GND/OPEN/REF/V
SUPPLY
5V BIAS
ON
______________________________________________________________________________________
AGND
AGND
OFF
Output Voltages Greater than 2V
CC
1000pF
1μF
C2
C3
100kΩ
1μF
R10
C1
PWR
Internal Integration
14
12
10
13
11
2
1
PGOOD
V
V
EN
SKIP
REF
REFIN
Controller with Dynamic REFIN
DD
CC
AGND
GND
MAX8792
Single Quick-PWM Step-Down
PWR
(EP)
ILIM
TON
BST
DH
LX
DL
FB
7
6
5
4
3
8
9
332kΩ
R
C
0.1μF
The MAX8792 disables the integrator by connecting the
amplifier inputs together at the beginning of all downward
REFIN transitions done in pulse-skipping mode. The inte-
grator remains disabled until 20µs after the transition is
completed (the internal target settles) and the output is in
regulation (edge detected on the error comparator).
PGOOD is the open-drain output that continuously
monitors the output voltage for undervoltage and over-
voltage conditions. PGOOD is actively held low in shut-
down (EN = GND), during soft-start, and soft-shutdown.
Approximately 200µs (typ) after the soft-start termi-
nates, PGOOD becomes high impedance as long as
the feedback voltage is above the UVP threshold
(REFIN - 200mV) and below the OVP threshold (REFIN
+ 300mV). PGOOD goes low if the feedback voltage
drops 200mV below the target voltage (REFIN) or rises
300mV above the target voltage (REFIN), or the SMPS
controller is shut down. For a logic-level PGOOD output
TON
BST
R5
OPEN
AGND
PWR
0Ω
R4
L1
REF
13.0kΩ
Power-Good Outputs (PGOOD)
R6
R7
20.0kΩ
AGND
SEE TABLE 1 FOR COMPONENT SELECTION.
PWR
C
C
PWR
OUT
IN
and Fault Protection
7V TO 24V
INPUT
5A (MAX)
OUTPUT
3.3V
17